The establishment of communications between microprocessors or microsequencers and other data processing units have long used the handshake technique. In this technique a request for access to a particular unit is made to the microprocessor or microsequencer and an acknowledge signal is sent back from the correct station when the communication channel is initiated. A simple handshake arrangement is adequate for many applications, but it is not suitable for very high speed operation when a microprocessor or microsequencer is coupled to a multiple number of functioning stations.